This invention is directed toward mounting a printing plate cylinder, for example a magnetic cylinder, to a rotatable drive shaft so that it can be adjusted both axially and circumferentially to bring the indicia to be printed into accurate registration.
One of the difficulties in using a printing plate cylinder, such as a magnetic cylinder, on printing presses or decorator machines and the like is that the printing or decorator plate has to be changed often. This requires either that the cylinder holding the plate be removed from its drive shaft then the plate removed, the cylinder cleaned, a new plate attached and the cylinder recoupled to the drive shaft or, the cylinder and plate be replaced with another cylinder with attached plate. In either case usually the printed material or indicia on the printing plate has to be aligned with or coordinated with or brought into registry with other printed material or indicia. U.S. Pat. No. 5,819,648 by Megyesi describes some of the problems associated with removal and replacement of printing plate cylinders for a decorator machine which is used to print or place indicia on the exterior of containers such as cans. Oftentimes this material is multicolored and so there has to be exact or very close registration amongst the various printing heads on a multihead printing machine. Other printing machines or presses have similar requirements for accurate registration and location of the printing plate cylinder with it associated attached printing plate. As further mentioned in the ""648 patent, some printing presses and decorator machines have straight or right angle cylindrical shafts and others have tapered shafts. There are benefits as well as detriments with each type. The straight right angle shaft generally allows for easier adjustability but repeated replacement causes wear. The tapered shaft generally avoids the wear problem but lacks the adjustability feature. The ""648 patent attempts to get the benefits of both types of shafts by using an inner member or sleeve which has a tapered or conical shaped axial bore to engage a tapered rotatable drive shaft and has an outer straight cylindrical surface for engaging a straight line or untapered axial bore of an outer member which is the printing plate cylinder. The outer printing plate cylinder is then adjusted with respect to the inner sleeve member while the latter is mated to or engaged with the tapered shaft. To replace the printing or decorator plate the asembled inner and outer members must be removed from the shaft.
U.S. Pat. No. 5,996,494 by one of the inventors in the instant application describes a first sleeve member having a tapered bore and a straight cylindrical outer surface with the bore engaging the tapered drive shaft in combination with a second sleeve member having a bore for engaging the outer surface of the first sleeve. The second sleeve has an outward flange or ring at one end containing a plurality of guide pins spaced around the ring extending in an axial direction and a set of additional axially extending guide pins at its other end. The printing plate cylinder has openings at one end for engaging the guide pins on the flange and an inward extending ring or flange with openings for engaging the other guide pins. Only the printing plate cylinder is removed to change plates. This arrangement reduces wear on the bore of the printing plate cylinder that normally occurs on repeated replacements but lacks adjustability which has to be provided in some other fashion.
The surface of the bore or annular surface of a sleeve comprises a bearing surface, preferably a roller bearing surface, which encompasses and engages an untapered rotatable drive shaft. For the purpose of this application, a bearing surface is meant to be a surface making intimate yet adjustable or slidable contact with another surface. In this case it is the annular surface, or portion thereof, of the bore of the sleeve having bearing surface contact with the outer surface of the untapered rotatable drive shaft. The outer surface of the right angle or untapered sleeve is coupled to the straight or untapered bore of a printing plate cylinder. The bearing surface of the sleeve bore in contact with the shaft permits the sleeve and the attached printing plate cylinder to be adjusted both axially and circumferentially with respect to the shaft to bring the indicia or design carried by the printing plate into exact register each time the plate cylinder is removed and replaced.
In the preferred embodiment the sleeve comprises a commercially available linear bearing which is press-fitted into the bore of the printing plate cylinder so essentially it becomes fixedly attached to the printing plate cylinder. The bearing surface allows the printing plate cylinder, with attached plate, to be adjusted axially and circumferentially each time it is replaced.